Animating soft substances with implicit surfaces

This paper presents a hybrid model for animation of soft inelastic substance which undergo topological changes, e.g. separation and fusion and which fit with the objects they are in contact with. The model uses a particle system coated with a smooth iso-surface that is used for performing collision detection, precise contact modeling and integration of response forces. The animation technique solves three problems inherent in implicit modeling. Firstly, local volume controllers are defined to insure constant volume deformation, even during highly inelastic processes such as splitting or fusion. Secondly, we avoid unwanted distance blending between disconnected pieces of the same substance. Finally, we simulate both collisions and progressive merging under compression between implicit surfaces that do not blend together. Parameter tuning is facilitated by the layered model and animation is generated at interactive rates.